Magnetic random access memory (MRAM) cells using the so-called self-referenced reading operation typically comprise a magnetic tunnel junction formed of a magnetic storage layer having a magnetization which direction can be changed from a first stable direction to a second stable direction, a thin insulating layer, and a sense layer having a reversible direction. Self-referenced MRAM cells allows for performing the write and read operation with low power consumption and an increased speed.
However, during the read operation a dipolar coupling between the storage and sense layers occurs due to local magnetic stray field, coupling the magnetization of the sense layer with the one of the storage layer in a closed magnetic flux configuration. Switching the sense layer magnetization during the read operation will then require applying a magnetic field high enough to overcome the dipolar coupling. The dipolar coupling results in a shift (or bias) of the hysteresis loop when applying a field cycle to measure the hysteresis loop of the sense layer. This dipolar coupling depends on the thickness and magnetization of the storage and sense layers, and on the size of the magnetic tunnel junction. In particular, dipolar coupling increases with decreasing the magnetic tunnel junction diameter and can thus become a major issue when scaling down the MRAM cell.
US20090190390 concerns an MRAM cell comprising a first magnetic layer structure having a first magnetization along a first axis; a second magnetic layer structure, and a non-magnetic spacer layer between the first and second magnetic layer structure. The second magnetic layer structure has a second magnetization along a second axis that is arranged at an angle with regard to the first axis such that, by changing the direction of the second magnetization, the direction of the first magnetization along the first axis can be determined.